Science (English Medium) Class 12 - CBSE Question Bank Solutions

Name the parts of an angiosperm flower in which development of male and female gametophyte take place.

In which way has the study of biology helped us to control infectious diseases?

List the three states the annuals and biennial angiosperms have to pass through during their life cycle.

By taking two examples explain how has bio-fortification helped in improving food quality.

In a flowering plant a microspore mother cell produces four male gametophytes while a megapore mother cell forms only one female gametophyte. Explain

Read the statement and answer the questions that follow.

A flower of brinjal has 520 ovules in its ovary. However, it produces a fruit with only 480 viable seeds.

(a) What could have prevented the rest of the 40 ovules from maturing into viable seeds? Explain giving a reason.

(b) Describe the development of a dicot embryo in a viable seed.

(c) Why certain angiospermic seed albuminous while others are exalbuminous? Explain.

A capsicum flower has 240 ovules in its ovary. But, it produces a fruit with only 180 viable seeds.
 

Name the following:  Any one inter-specific hybrid mammal.

Give an example of an angiosperm seed that has a perisperm. Name the part the perisperm develops from.

Explain the events upto double fertilisation after the pollen tube enters one of the synergids in an ovule of an angiosperm.
 

Bottled fruit juices are clearer as compared to those made at home. Explain.

Answer the following question based on Meselson and Stahl's experiment on E. coli :

Why did they allow the synthesis of the light and the heavy DNA molecules in the organism?

Answer the following question based on Meselson and Stahl's experiment on E. coli :

How did they distinguish the heavy DNA molecules from the light DNA molecules? Explain.

Answer the following question based on Meselson and Stahl's experiment on E. coli :

Write the conclusion the scientists arrived at, at the end of the experiment.

A typical flower has ______ different kinds of whorl.

The membranous cover of the ovum at ovulation is ______.

Correct sequence in development is ______.

______ is a lytic enzyme released by the sperm.

How does human sperm locomote?

Cryptorchidism is a condition where ______.